Silica particles and method for producing the same
Silica particles include a nitrogen-containing compound. When the volumes of pores having a diameter of 1 nm or more and 50 nm or less, the volumes being determined from a pore size distribution curve of the silica particles before and after the silica particles are baked at 350° C., the pore size distribution curve being obtained by nitrogen gas adsorption, are defined as A and B, respectively, B/A is 1.2 or more and 5 or less and B is 0.2 cm 3 /g or more and 3 cm 3 /g or less.
1. Silica particles comprising:
a nitrogen-containing compound,
wherein, when A is a volume of pores having a diameter of 1 nm or more and 50 nm or less before the silica particles are baked at 350° C. and B is a volume of pores having a diameter of 1 nm or more and 50 nm or less after the silica particles are baked at 350° C., the volumes being determined from a pore size distribution curve obtained by nitrogen gas adsorption, B/A is 1.2 or more and 5 or less and B is 0.2 cm 3 /g or more and 3 cm 3 /g or less, and
wherein the pores are composed of a product of a reaction of a trifunctional silane coupling agent, and
wherein the nitrogen-containing compound is at least one selected from the group consisting of a quaternary ammonium salt including molybdenum and a mixture of a quaternary ammonium salt with a metal oxide including molybdenum.
2. The silica particles according to claim 1 ,
wherein the B/A is 1.4 or more and 3 or less.
3. The silica particles according to claim 1 ,
wherein the B is 0.3 cm 3 /g or more and 1.8 cm 3 /g or less.
4. The silica particles according to claim 1 ,
the silica particles having a number average size of 10 nm or more and 200 nm or less.
5. The silica particles according to claim 4 ,
wherein the number average size is 10 nm or more and 80 nm or less.
6. The silica particles according to claim 1 ,
the silica particles having an average circularity of 0.60 or more and 0.96 or less.
7. The silica particles according to claim 1 ,
the silica particles having an average circularity of 0.70 or more and 0.92 or less.
8. The silica particles according to claim 1 ,
the silica particles having a volume resistivity of 1.0×10 7 Ω·cm or more and 1.0×10 11.5 Ω·cm or less.
9. The silica particles according to claim 1 ,
wherein, when volume resistivity values of the silica particles, the volume resistivity values being measured before and after the silica particles are baked at 350° C., are defined as Ra and Rb, respectively, Ra/Rb is 0.01 or more and 0.8 or less.
10. The silica particles according to claim 1 ,
wherein a ratio of an integral C of a signal observed at a chemical shift of −50 ppm or more and −75 ppm or less in a 29 Si solid-state nuclei magnetic resonance (NMR) spectrum of the silica particles, the 29 Si solid-state NMR spectrum being obtained by cross polarization/magic angle spinning (CP/MAS), to an integral D of a signal observed at a chemical shift of −90 ppm or more and −120 ppm or less in the 29 Si solid-state NMR spectrum, that is, C/D, is 0.10 or more and 0.75 or less.
11. The silica particles according to claim 1 ,
wherein a content of the nitrogen-containing compound is 0.008% by mass or more and 0.45% by mass or less of the amount of the silica particles in terms of nitrogen atoms.
12. The silica particles according to claim 1 ,
wherein a ratio of a net intensity of molybdenum to a net intensity of silicon which are determined by X-ray fluorescence analysis (Mo/Si) is 0.035 or more and 0.35 or less.
13. The silica particles according to claim 1 ,
wherein the quaternary ammonium salt is represented by following Formula (AM):
wherein, in Formula (AM), R 1 , R 2 , R 3 , and R 4 each independently represent a hydrogen atom or an alkyl, aralkyl, or aryl group that may include a substituent; and X − represents an anion, wherein at least one of the R 1 , R 2 , R 3 , and R 4 represents an alkyl, aralkyl, or aryl group that may include the substituent; two or more of the R 1 , R 2 , R 3 , and R 4 may be joined to one another to form an aliphatic, aromatic, or hetero ring; and the substituent is independently selected from the group consisting of a nitrile group, a carbonyl group, an ether group, an amide group, a siloxane group, a silyl group, and a silanealkoxy group.
14. The silica particles according to claim 13 ,
wherein the anion represented by X − is an inorganic anion selected from the groups consisting of MoO 4 2− , Mo 2 O 7 2− , Mo 3 O 10 2− , Mo 4 O 13 2− , Mo 7 O 24 2− , and Mo 8 O 26 4− .
15. The silica particles according to claim 1 ,
wherein the nitrogen-containing compound is the mixture of the quaternary ammonium salt with the metal oxide including molybdenum, and
the metal oxide including molybdenum is selected from the group consisting of a molybdenum oxide, an alkali metal salt of molybdenum acid, and an alkaline-earth metal salt of molybdenum acid.
16. The silica particles according to claim 1 ,
wherein the pores are composed of a product of reaction between the functional groups of the trifunctional silane coupling agent.
17. A method for producing the silica particles according to claim 1 , the method comprising:
forming the pores composed of the product of reaction of the trifunctional silane coupling agent on at least a part of surfaces of silica base particles; and
adsorbing a nitrogen-containing compound onto at least a part of the pores formed in the product of reaction of the trifunctional silane coupling agent.